This switches clang to use the data layouts from TargetParser, instead
of maintaining its own copy of data layouts, which are required to match
the backend data layouts.
For now I've kept explicit calls to resetDataLayout(), just with the
argument implied by the triple and ABI. Ideally this would happen
automatically, but the way these classes are initialized currently
doesn't offer a great place to do this.
Previously resetDataLayout() also set the UserLabelPrefix. I've
separated this out, with a reasonable default so that most targets don't
need to worry about it.
I've kept the explicit data layouts for TCE and SPIR (without the V).
These seem to not correspond to real LLVM targets.
I've also fixed the XCore data layout in TargetParser, which was
incorrectly set to the same one as Xtensa. It was previously unused.
As the data layout a few lines further up specifies, the int, long and
pointer alignment should be 16 instead of the default of 32.
The long long alignment is also incorrect, but that would require a
change to the data layout as well.
Comparison with GCC, which consistently uses 2 byte alignment:
https://gcc.godbolt.org/z/K3x6a7dEf At least based on some spot checks,
the changes to bit field layout also make use match GCC now.
This was found by https://github.com/llvm/llvm-project/pull/144720.
These are identified by misc-include-cleaner. I've filtered out those
that break builds. Also, I'm staying away from llvm-config.h,
config.h, and Compiler.h, which likely cause platform- or
compiler-specific build failures.
This both reapplies #118734, the initial attempt at this, and updates it
significantly.
First, it uses the newly added `StringTable` abstraction for string
tables, and simplifies the construction to build the string table and
info arrays separately. This should reduce any `constexpr` compile time
memory or CPU cost of the original PR while significantly improving the
APIs throughout.
It also restructures the builtins to support sharding across several
independent tables. This accomplishes two improvements from the
original PR:
1) It improves the APIs used significantly.
2) When builtins are defined from different sources (like SVE vs MVE in
AArch64), this allows each of them to build their own string table
independently rather than having to merge the string tables and info
structures.
3) It allows each shard to factor out a common prefix, often cutting the
size of the strings needed for the builtins by a factor two.
The second point is important both to allow different mechanisms of
construction (for example a `.def` file and a tablegen'ed `.inc` file,
or different tablegen'ed `.inc files), it also simply reduces the sizes
of these tables which is valuable given how large they are in some
cases. The third builds on that size reduction.
Initially, we use this new sharding rather than merging tables in
AArch64, LoongArch, RISCV, and X86. Mostly this helps ensure the system
works, as without further changes these still push scaling limits.
Subsequent commits will more deeply leverage the new structure,
including using the prefix capabilities which cannot be easily factored
out here and requires deep changes to the targets.
Reverts llvm/llvm-project#118734
There are currently some specific versions of MSVC that are miscompiling
this code (we think). We don't know why as all the other build bots and
at least some folks' local Windows builds work fine.
This is a candidate revert to help the relevant folks catch their
builders up and have time to debug the issue. However, the expectation
is to roll forward at some point with a workaround if at all possible.
The Clang binary (and any binary linking Clang as a library), when built
using PIE, ends up with a pretty shocking number of dynamic relocations
to apply to the executable image: roughly 400k.
Each of these takes up binary space in the executable, and perhaps most
interestingly takes start-up time to apply the relocations.
The largest pattern I identified were the strings used to describe
target builtins. The addresses of these string literals were stored into
huge arrays, each one requiring a dynamic relocation. The way to avoid
this is to design the target builtins to use a single large table of
strings and offsets within the table for the individual strings. This
switches the builtin management to such a scheme.
This saves over 100k dynamic relocations by my measurement, an over 25%
reduction. Just looking at byte size improvements, using the `bloaty`
tool to compare a newly built `clang` binary to an old one:
```
FILE SIZE VM SIZE
-------------- --------------
+1.4% +653Ki +1.4% +653Ki .rodata
+0.0% +960 +0.0% +960 .text
+0.0% +197 +0.0% +197 .dynstr
+0.0% +184 +0.0% +184 .eh_frame
+0.0% +96 +0.0% +96 .dynsym
+0.0% +40 +0.0% +40 .eh_frame_hdr
+114% +32 [ = ] 0 [Unmapped]
+0.0% +20 +0.0% +20 .gnu.hash
+0.0% +8 +0.0% +8 .gnu.version
+0.9% +7 +0.9% +7 [LOAD #2 [R]]
[ = ] 0 -75.4% -3.00Ki .relro_padding
-16.1% -802Ki -16.1% -802Ki .data.rel.ro
-27.3% -2.52Mi -27.3% -2.52Mi .rela.dyn
-1.6% -2.66Mi -1.6% -2.66Mi TOTAL
```
We get a 16% reduction in the `.data.rel.ro` section, and nearly 30%
reduction in `.rela.dyn` where those reloctaions are stored.
This is also visible in my benchmarking of binary start-up overhead at
least:
```
Benchmark 1: ./old_clang --version
Time (mean ± σ): 17.6 ms ± 1.5 ms [User: 4.1 ms, System: 13.3 ms]
Range (min … max): 14.2 ms … 22.8 ms 162 runs
Benchmark 2: ./new_clang --version
Time (mean ± σ): 15.5 ms ± 1.4 ms [User: 3.6 ms, System: 11.8 ms]
Range (min … max): 12.4 ms … 20.3 ms 216 runs
Summary
'./new_clang --version' ran
1.13 ± 0.14 times faster than './old_clang --version'
```
We get about 2ms faster `--version` runs. While there is a lot of noise
in binary execution time, this delta is pretty consistent, and
represents over 10% improvement. This is particularly interesting to me
because for very short source files, repeatedly starting the `clang`
binary is actually the dominant cost. For example, `configure` scripts
running against the `clang` compiler are slow in large part because of
binary start up time, not the time to process the actual inputs to the
compiler.
----
This PR implements the string tables using `constexpr` code and the
existing macro system. I understand that the builtins are moving towards
a TableGen model, and if complete that would provide more options for
modeling this. Unfortunately, that migration isn't complete, and even
the parts that are migrated still rely on the ability to break out of
the TableGen model and directly expand an X-macro style `BUILTIN(...)`
textually. I looked at trying to complete the move to TableGen, but it
would both require the difficult migration of the remaining targets, and
solving some tricky problems with how to move away from any macro-based
expansion.
I was also able to find a reasonably clean and effective way of doing
this with the existing macros and some `constexpr` code that I think is
clean enough to be a pretty good intermediate state, and maybe give a
good target for the eventual TableGen solution. I was also able to
factor the macros into set of consistent patterns that avoids a
significant regression in overall boilerplate.
This patch adds `CC_M68kRTD`, which will be used on function if either
`__attribute__((m68k_rtd))` is presented or `-mrtd` flag is given.
Differential Revision: https://reviews.llvm.org/D149867
Use `DefineStd` for target-specific macros such that GNU-style definitions
can be correctly toggled.
Differential Revision: https://reviews.llvm.org/D158698
Change the return type of `getClobbers` function from `const char*`
to `std::string_view`. Update the function usages in CodeGen module.
The reasoning of these changes is to remove unsafe `const char*`
strings and prevent unnecessary allocations for constructing the
`std::string` in usages of `getClobbers()` function.
Differential Revision: https://reviews.llvm.org/D148799
This patch mechanically replaces None with std::nullopt where the
compiler would warn if None were deprecated. The intent is to reduce
the amount of manual work required in migrating from Optional to
std::optional.
This is part of an effort to migrate from llvm::Optional to
std::optional:
https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716
Fixes PR51626.
The M68k requires that all instruction, word and long word reads are
aligned to word boundaries. From the 68020 onwards, there is a
performance benefit from aligning long words to long word boundaries.
The M68k uses the same data layout for pointers and integers.
In line with this, this commit updates the pointer data layout to
match the layout already set for 32-bit integers: 32:16:32.
Differential Revision: https://reviews.llvm.org/D108792
GCC allows each target to define a set of non-letter and non-digit
escaped characters for inline assembly that will be replaced by another
string (They call this "punctuation" characters. The existing "%%" and
"%{" -- replaced by '%' and '{' at the end -- can be seen as special
cases shared by all targets).
This patch implements this feature by adding a new hook in `TargetInfo`.
Differential Revision: https://reviews.llvm.org/D103036
This patch adds supports for inline assembly operands and some simple
operand constraints, including register and constant operands.
Differential Revision: https://reviews.llvm.org/D102585
Clang _requires_ every target to provide a va_list kind so we shouldn't
put a llvm_unreachable there. Using `VoidPtrBuiltinVaList` because m68k
doesn't have any special ABI for variadic args.
This is the first patch supporting M68k in Clang
- Register M68k as a target
- Target specific CodeGen support
- Target specific attribute support
Authors: myhsu, m4yers, glaubitz
Differential Revision: https://reviews.llvm.org/D88393
